The ‘schiscetta’, to put it in the Milanese way, must be treated with respect. If the lunchbox is made of plastic and is heated inappropriately in the microwave, there is a risk that it will release microplastics into the environment. This is demonstrated by a study coordinated by the State University of Milan in collaboration with the University of Milan-Bicocca, conducted in Eos, a company that develops a technology called Spes for the optical characterization of dust, created in the physics laboratories of UniMi. The research is published in the journal ‘Particles and Particle Systems Characterization’.
The idea of checking whether plastic food containers heated in the microwave released micro and nanoplastics – explain Statale and Bicocca – started from Eos, which used Spes technology highlighting the systematic formation of plastic nano and microspheres during the heating of pure water, a controlled experiment aimed at simulating what happens when food is heated. “Spes is an innovative method that allows you to classify nano and micro particles in a very precise and complete way”, says Marco Pallavera, Research & Development director of Eos, creator of the measurement protocol used in the study and first author of the article. “The study, begun almost out of curiosity – underlines Tiziano Sanvito, who has administered Eos since its foundation in 2014 – immediately showed the adequacy of our method to build a solid and reliable protocol for the problem under study”.
“The data taken from Eos immediately showed a strong solidity, fundamental for approaching a delicate problem like this”, confirms Marco Potenza who invented the Spes technique, professor of Optics of the UniMi Physics Department, head of the Optical Instrumentation Laboratory and director of Cimaina (Interdepartmental Center for Nanostructured Materials and Interfaces). After many cross-checks on the experimental procedures, the researchers came to the conclusion that in fact, “by heating pure water in food containers, nano and microspheres composed of the material the container itself is made of are released: polypropylene, a biocompatible material that has the characteristic of melting between 90 and 110 °C. By bringing the water to the boil, therefore, a small part of the polypropylene melts and then solidifies again in the water”.
The results – reports a note – were also analyzed and studied in detail by Llorenç Cremonesi and Claudio Artoni of the EuroCold laboratory, at the Department of Environmental and Earth Sciences of UniMiB, and accompanied by electron microscope images taken by Andrea Falqui , professor of the Physics Department of the State University.
“It is interesting to note – specifies Sanvito – that various manufacturers specify not to bring the containers above 90 °C, or not to heat them for too long in the microwave, or even not to use the appliance at maximum power. Therefore, following these indications, the effect does not occur”. Conversely, concludes Potenza, “the nano- and micro-particles produced will contribute to the dispersion of plastic in the environment which characterizes the modern world”.
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